This revised Immunization Practices Advisory Committee (ACIP)
recommendation on mumps vaccine updates the 1982 recommendation
(1).
Changes include: a discussion of the evolving epidemiologic
characteristics of mumps, introduction of a cutoff of 1957 as the
oldest birth cohort for which mumps vaccination is routinely
recommended, and more aggressive outbreak-control measures.
Although
there are no major changes in vaccination strategy, these revised
recommendations place a greater emphasis on vaccinating susceptible
adolescents and young adults.
INTRODUCTION
Mumps Disease

Mumps disease is generally self-limited, but it may be moderately
debilitating. Naturally acquired mumps infection, including the
estimated 30% of infections that are subclinical, confers
long-lasting
immunity.

Among the reported mumps-associated complications, strong
epidemiologic and laboratory evidence for an association with
meningoencephalitis, deafness, and orchitis has been reported (2).
Meningeal signs appear in up to 15% of cases. Reported rates of
mumps
encephalitis range as high as five cases per 1000 reported mumps
cases.
Permanent sequelae are rare, but the reported encephalitis
case-fatality rate has averaged 1.4%. Although overall mortality is
low, death due to mumps infection is much more ikely to occur in
adults; about half of mumps-associated deaths have been in persons
greater than or equal to 20 years old (2). Sensorineural deafness
is
one of the most serious of the rare complications involving the
central
nervous system (CNS). It occurs with an estimated frequency of
0.5-5.0
per 100,000 reported mumps cases. Orchitis (usually unilateral) has
been reported as a complication in 20%-30% of clinical mumps cases
in
postpubertal males (3). Some testicular atrophy occurs in about 35%
of
cases of mumps orchitis, but sterility rarely occurs. Symptomatic
involvement of other organs has been observed less frequently.
There
are limited experimental, clinical, and epidemiologic data that
suggest
permanent pancreatic damage may result from injury caused by direct
viral invasion. Further research is needed to determine whether
mumps
infection contributes to the pathogenesis of diabetes mellitus.
Mumps
infection during the first trimester of pregnancy may increase the
rate
of spontaneous abortion (reported to be as high as 27%). There is
no
evidence that mumps during pregnancy causes congenital
malformations.
Epidemiology

Following the introduction of the live mumps virus vaccine in 1967
and
recommendation of its routine use in 1977, the incidence rate of
reported mumps cases decreased steadily in the United States. In
1985,
a record low of 2982 cases was reported, representing a 98% decline
from the 185,691 cases reported in 1967. However, between 1985 and
1987, a relative resurgence of mumps occurred, with 7790 cases
reported
in 1986 and 12,848 cases in 1987 (4). During this 3-year period,
the
annual reported incidence rate rose almost fivefold, from 1.1 cases
per
100,000 population to 5.2 cases per 100,000 population. In 1988, a
provisional total of 4730 cases was reported, representing a 62%
decrease from 1987.
As in the prevaccine era, the majority of reported mumps cases
still
occur in school-aged children (5-14 years of age). Almost 60% of
reported cases occurred in this population between 1985 and 1987,
compared with an average of 75% of reported cases between 1967 and
1971, the first 5-year period postlicensure. However, for the first
time since mumps became a reportable disease, the reported peak
incidence rate shifted from 5-9-year-olds to older age groups for
two
consecutive years (1986 and 1987). Persons greater than or equal to
15
years of age accounted for more than one third of the reported
total
between 1985 and 1987; in 1967-1971, an average of only 8% of
reported
cases occurred among this population. Although reported mumps
incidence
increased in all age groups from 1985 to 1987, the most dramatic
increases were among 10-14-year-olds (almost a sevenfold increase)
and
15-19-year-olds (more than an eightfold increase).

The increased occurrence of mumps in susceptible adolescents and
young
adults has been demonstrated in several recent outbreaks in high
schools and on college campuses (5,6) and in occupational settings
(7).
Nonetheless, despite this age shift in reported mumps, the overall
reported risk of disease in persons 10-14 and greater than or equal
to
15 years of age is still lower than that in the prevaccine and
early
postvaccine era.

Consistent with previous findings (8), reported incidence rates
are
lower in states with comprehensive school immunization laws. The
District of Columbia and 14 states that routinely reported mumps
cases
in 1987 had comprehensive laws that require proof of immunity
against
mumps for school attendance from kindergarten through grade 12
(K-12).
In these 15 areas, the incidence rate in 1987 was 1.1 mumps cases
per
100,000 population. In contrast, among the other states that
routinely
reported mumps cases in 1987, mumps incidence was highest in the 14
states without requirements for mumps vaccination (11.5 cases per
100,000 population), and intermediate (6.2 cases per 100,000
population) in the 18 states with partial vaccination requirements
for
school attendance (i.e., those that include some children but do
not
comprehensively include K-12). Furthermore, the shift in
age-specific
risk noted above occurred only in states without comprehensive K-12
school vaccination requirements.

Both the shift in risk to older persons and the relative
resurgence of
reported mumps activity noted in recent years are attributable to
the
relatively underimmunized cohort of children born between 1967 and
1977
(9). There is no evidence of waning immunity in vaccinated persons.
During 1967-1977, the risk of exposure to mumps declined rapidly
even
though vaccination of children against mumps was only gradually
being
accepted as a routine practice. Simultaneously, mumps vaccine
coverage
did not reach levels greater than 50% in any age group until 1976
(5-9-year-olds); in persons 15-19 years old, vaccine coverage did
not
reach these levels until 1983. This lag in coverage relative to
measles
and rubella vaccines reflects the lack of an ACIP recommendation
for
routine mumps vaccine until 1977 and the lack of emphasis in ACIP
recommendations on vaccination beyond toddler age until 1980. These
facts and the observed shift in risk to older persons in states
without
comprehensive mumps immunization school laws provide further
evidence
that a failure to vaccinate, rather than vaccine failure, is
primarily
responsible for the recently observed changes in mumps occurrence.
MUMPS VIRUS VACCINE

A killed mumps virus vaccine was licensed for use in the United
States
from 1950 through 1978. This vaccine induced antibody, but the
immunity
was transient. The number of doses of killed mumps vaccine
administered
between licensure of live attenuated mumps vaccine in 1967 until
1978
is unknown but appears to have been limited.

Mumps virus vaccine* is prepared in chick-embryo cell culture.
More
than 84 million doses were distributed in the United States from
its
introduction in December 1967 through 1988. The vaccine produces a
subclinical, noncommunicable infection with very few side effects.
Mumps vaccine is available both in monovalent (mumps only) form and
in
combinations: mumps-rubella and measles-mumps-rubella (MMR)
vaccines.

The vaccine is approximately 95% efficacious in preventing mumps
disease (10,11); greater than 97% of persons known to be
susceptible to
mumps develop measurable antibody following vaccination (12).
Vaccine-induced antibody is protective and long-lasting (13,14),
although of considerably lower titer than antibody resulting from
natural infection (12). The duration of vaccine-induced immunity is
unknown, but serologic and epidemiologic data collected during 20
years
of live vaccine use indicate both the persistence of antibody and
continuing protection agains infection. Estimates of clinical
vaccine
efficacy ranging from 75% to 95% have been calculated from data
collected in outbreak settings using different epidemiologic study
designs (8,15).
Vaccine Shipment and Storage

Administration of improperly stored vaccine may fail to protect
against mumps. During storage before reconstitution, mumps vaccine
must
be kept at 2-8 C (35.6- 46.4 F) or colder. It must also be
protected
from light, which may inactivate the virus. Vaccine must be shipped
at
10 C (50 F) or colder and may be shipped on dry ice. After
reconstitution, the vaccine should be stored in a dark place at 2-8
C
(35.6-46.4 F) and discarded if not used within 8 hours.
VACCINE USAGE

(See also the current ACIP statement, "General Recommendations on
Immunization" (16).)
General Recommendations

Susceptible children, adolescents, and adults should be vaccinated
against mumps, unless vaccination is contraindicated. Mumps vaccine
is
of particular value for children approaching puberty and for
adolescents and adults who have not had mumps. MMR vaccine is the
vaccine of choice for routine administration and should be used in
all
situations where recipients are also likely to be susceptible to
measles and/or rubella. The favorable benefit-cost ratio for
routine
mumps immunization is more marked when vaccine is administered as
MMR
(17). Persons should be considered susceptible to mumps unless they
have documentation of 1) physician-diagnosed mumps, 2) adequate
immunization with live mumps virus vaccine on or after their first
birthday, or 3) laboratory evidence of immunity. Because live mumps
vaccine was not used routinely before 1977 and because the peak
age-specific incidence was in 5-9-year-olds before the vaccine was
introduced, most persons born before 1957 are likely to have been
infected naturally between 1957 and 1977. Therefore, they generally
may
be considered to be immune, even if they may not have had
clinically
recognizable mumps disease. However, this cutoff date for
susceptibility is arbitrary. Although outbreak-control efforts
should
be focused on persons born after 1956, these recommendations do not
preclude vaccination of possibly susceptible persons born before
1957
who may be exposed in outbreak settings.
Persons who are unsure of their mumps disease history and/or
mumps
vaccination history should be vaccinated. There is no evidence that
persons who have previously either received mumps vaccine or had
mumps
are at any increased risk of local or systemic reactions from
receiving
live mumps vaccine. Testing for susceptibility before vaccination,
especially among adolescents and young adults, is not necessary. In
addition to the expense, some tests (e.g., mumps skin test and the
complement-fixation antibody test) may be unreliable, and tests
with
established reliability (neutralization, enzyme immunoassay, and
radial
hemolysis antibody tests) are not readily available.

Dosage. A single dose of vaccine in the volume specified by the
manufacturer should be administered subcutaneously. While not
recommended routinely, intramuscular vaccination is effective and
safe.

Age. Live mumps virus vaccine is recommended at any age on or
after
the first birthday for all susceptible persons, unless a
contraindication exists. Under routine circumstances, mumps vaccine
should be given in combination with measles and rubella vaccines as
MMR, following the currently recommended schedule for
administration of
measles vaccine. It should not be administered to infants less than
12
months old because persisting maternal antibody might interfere
with
seroconversion. To insure immunity, all persons vaccinated before
the
first birthday should be revaccinated on or after the first
birthday.
Persons Exposed to Mumps

Use of Vaccine. When given after exposure to mumps, live mumps
virus
vaccine may not provide protection. However, if the exposure did
not
result in infection, vaccine should induce protection against
infection
from subsequent exposures. There is no evidence that the risk of
vaccine-associated adverse events increases if vaccine is
administered
to persons incubating disease.

Use of Immune Globulin. Immune globulin (IG) has not been
demonstrated
to be of established value in postexposure prophylaxis and is not
recommended. Mumps immune globulin has not been shown to be
effective
and is no longer available or licensed for use in the United
States.
Adverse Effects of Vaccine Use

In field trials before licensure, illnesses did not occur more
often
in vaccinees than in unvaccinated controls (18). Reports of
illnesses
following mumps vaccination have mainly been episodes of parotitis
and
low-grade fever. Allergic reactions including rash, pruritus, and
purpura have been temporally associated with mumps vaccination but
are
uncommon and usually mild and of brief duration. The reported
occurrence of encephalitis within 30 days of receipt of a
mumps-containing vaccine (0.4 per million doses) is not greater
than
the observed background incidence rate of CNS dysfunction in the
normal
population. Other manifestations of CNS involvement, such as
febrile
seizures and deafness, have also been infrequently reported.
Complete
recovery is usual. Reports of nervous system illness following
mumps
vaccination do not necessarily denote an etiologic relationship
between
the illness and the vaccine.
Contraindications to Vaccine Use

Pregnancy. Although mumps vaccine virus has been shown to infect
the
placenta and fetus (19), there is no evidence that it causes
congenital
malformations in humans. However, because of the theoretical risk
of
fetal damage, it is prudent to avoid giving live virus vaccine
to pregnant women. Vaccinated women should avoid pregnancy for 3
months
after vaccination. Routine precautions for vaccinating postpubertal
women include asking if they are or may be pregnant, excluding
those
who say they are, and explaining the theoretical risk to those who
plan
to receive the vaccine. Vaccination during pregnancy should not be
considered an indication for termination of pregnancy. However, the
final decision about interruption of pregnancy must rest with the
individual patient and her physician.

Severe Febrile Illness. Vaccine administration should not be
postponed
because of minor or intercurrent febrile illnesses, such as mild
upper
respiratory infections. However, vaccination of persons with severe
febrile illnesses should generally be deferred until they have
recovered.

Allergies. Because live mumps vaccine is produced in chick-embryo
cell
culture, persons with a history of anaphylactic reactions (hives,
swelling of the mouth and throat, difficulty breathing,
hypotension, or
shock) after egg ingestion should be vaccinated only with caution
using
published protocols (20,21). Known allergic children should not
leave
the vaccination site for 20 minutes. Evidence indicates that
persons
are not at increased risk if they have egg allergies that are not
anaphylactic in nature. Such persons may be vaccinated in the usual
manner. There is no evidence to indicate that persons with
allergies to
chickens or feathers are at increased risk of reaction to the
vaccine.

Since mumps vaccine contains trace amounts of neomycin (25 ug),
persons who have experienced anaphylactic reactions to topically or
systemically administered neomycin should not receive mumps
vaccine.
Most often, neomycin allergy is manifested as a contact dermatitis,
which is a delayed-type (cell-mediated) immune response, rather
than
anaphylaxis. In such persons, the adverse reaction, if any, to 25
ug of
neomycin in the vaccine would be an erythematous, pruritic nodule
or
papule at 48-96 hours. A history of contact dermatitis to neomycin
is
not a contraindication to receiving mumps vaccine. Live mumps virus
vaccine does not contain penicillin.

Recent IG Injection. Passively acquired antibody can interfere
with
the response to live, attenuated-virus vaccines. Therefore, mumps
vaccine should be given at least 2 weeks before the administration
of
IG or deferred until approximately 3 months after the
administration of
IG.

Altered Immunity. In theory, replication of the mumps vaccine
virus
may be potentiated in patients with immune deficiency diseases and
by
the suppressed immune responses that occur with leukemia, lymphoma,
or
generalized malignancy or with therapy with corticosteroids,
alkylating
drugs, antimetabolites, or radiation. In general, patients with
such
conditions should not be given live mumps virus vaccine. Because
vaccinated persons do not transmit mumps vaccine virus, the risk of
mumps exposure for those patients may be reduced by vaccinating
their
close susceptible contacts.

An exception to these general recommendations is in children
infected
with human immunodeficiency virus (HIV); all asymptomatic
HIV-infected
children should receive MMR at 15 months of age (22). If measles
vaccine is administered to symptomatic HIV-infected children, the
combination MMR vaccine is generally preferred (23).
Patients with leukemia in remission whose chemotherapy has been
terminated for at least 3 months may also receive live mumps virus
vaccine. Short-term ( less than 2 weeks' duration) corticosteroid
therapy, topical steroid therapy (e.g., nasal, skin), and
intraarticular, bursal, or tendon injection with corticosteroids do
not
contraindicate mumps vaccine administration. However, mumps vaccine
should be avoided if systemic immunosuppressive levels are reached
by
prolonged, extensive, topical application.

Other. There is no known association between mumps vaccination and
pancreatic damage or subsequent development of diabetes mellitus
(24).
MUMPS CONTROL

The principal strategy to prevent mumps is to achieve and maintain
high immunization levels, primarily in infants and young children.
Universal immunization as a part of good health care should be
routinely carried out in physicians' offices and public health
clinics.
Programs aimed at vaccinating children with MMR should be
established
and maintained in all communities. In addition, all other persons
thought to be susceptible should be vaccinated unless otherwise
contraindicated. This is especially important for adolescents and
young
adults in light of the recently observed increase in risk of
disease in
these populations.

Because access to some population subgroups is limited, the ACIP
recommends taking maximal advantage of clinic visits to vaccinate
susceptible persons greater than or equal to 15 months of age by
administering MMR, diphtheria-tetanus-pertussis (DTP), and oral
polio
vaccine (OPV) simultaneously if all are needed. Health agencies
should
take necessary steps, including the development, adoption, and
enforcement of comprehensive immunization requirements, to ensure
that
all persons in schools at all grade levels and in day-care settings
are
protected against mumps. Similar requirements should be considered
for
colleges, as recommended by the American College Health Association
(25), and selected places of employment where persons in this age
cohort are likely to be concentrated or where the consequences of
disease spread may be more severe (e.g., medical-care settings).

In determining means to control mumps outbreaks, exclusion of
susceptible students from affected schools and schools judged by
local
public health authorities to be at risk for transmission should be
considered. Such exclusion should be an effective means of
terminating
school outbreaks and quickly increasing rates of immunization.
Excluded
students can be readmitted immediately after vaccination. Pupils
who
have been exempted from mumps vaccination because of medical,
religious, or other reasons should be excluded until at least 26
days
after the onset of parotitis in the last person with mumps in the
affected school. Experience with outbreak control for other
vaccine-preventable diseases indicates that almost all students who
are
excluded from the outbreak area because they lack evidence of
immunity
quickly comply with requirements and can be readmitted to school.
MUMPS DISEASE SURVEILLANCE AND REPORTING OF ADVERSE EVENTS

There is a continuing need to improve the reporting of mumps cases
and
complications and to document the duration of vaccine
effectiveness.
Thus, for areas in which mumps is a reportable disease, all
suspected
cases of mumps should be reported to local or state health
officials.
The National Childhood Vaccine Injury Compensation Program
established
by the National Childhood Vaccine Injury Compensation Act of 1986
requires physicians and other health-care providers who administer
vaccines to maintain permanent immunization records and to report
occurrences of certain adverse events to the U.S. Department of
Health
and Human Services. Recording and reporting requirements took
effect on
March 21, 1988. Reportable adverse events include those listed in
the
Act for mumps (26) and events specified in the manufacturer's
vaccine
package insert as contraindications to further doses of mumps
vaccine.

Although there eventually will be one system for reporting adverse
events following immunizations, two separate systems currently
exist.
The appropriate reporting method currently depends on the source of
funding used to purchase the vaccine (26). Events that occur after
receipt of a vaccine purchased with public (federal, state, and/or
local government) funds must be reported by the administering
health
provider to the appropriate local, county, or state health
department.
The state health department completes and submits the correct forms
to
CDC. Reportable events that follow administration of vaccines
purchased
with private money are reported by the health-care provider
directly to
the Food and Drug Administration.
RECOMMENDATIONS FOR INTERNATIONAL TRAVEL

Mumps is still endemic throughout most of the world. While
vaccination
against mumps is not a requirement for entry into any country,
susceptible children, adolescents, and adults would benefit by
being
vaccinated with a single dose of vaccine (usually as MMR), unless
contraindicated, before beginning travel. Because of concern about
inadequate seroconversion due to persisting maternal antibodies and
because the risk of serious disease from mumps infection is
relatively
low, persons less than 12 months of age need not be given mumps
vaccine
before travel.

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